SCIENCE.-SUPPLEMENT. 



FRIDAY, SEPTEMBER 17, 1886. 



PSYCH0PHY8ICS. 



This is a comparatively new science, although 

 its beginnings can be traced back into the last 

 century. But until comparatively recent. years it 

 occupied a subordinate position in speculative psy- 

 chology, and the phenomena constituting its prov- 

 ince were not assumed to be distinct enough for 

 separate investigation. At present, however, a 

 certain class of students are endeavoring, by ex- 

 periment, to give its method and results that exact- 

 ness which is supposed to describe the function of 

 science proper. The province of science has become 

 more exactly defined in the course of its develop- 

 ment until the proper criterion of its function is 

 that measurement and demonstration of its results 

 which takes its theories out of the reach of proba- 

 bilities and conjecture and establishes them upon 

 a basis of certainty. Introspective psychology has 

 either presented unsatisfactory results, or the uni- 

 versal prepossession for experimental effects has 

 ■desired to represent it so, and thereby contrast its 

 uncertainty with the tangible and demonstrable 

 products of exact science. However we may ac- 

 count for it, psychophysics has come in to dispute 

 the territory of the older psychology, at least in 

 the person of some of its admirers. It likes to 

 speak of purely introspective psychology as out of 

 date, and as if it were discredited merely because 

 it is of the past. Innovation and change have 

 predisposed inquirers to enthusiasm for the new, 

 perhaps because all the great triumphs of modern 

 science have been conquests over old views, or 

 deviations from them ; the old has lost its prestige. 

 Nothing has suffered more from this spirit than 

 * the old psychology,' as it is called by the admirers 

 of psychophysics. The latter is taking rapid pos- 

 session of scientific and philosophic interest, until 

 students of the older philosophy are beginning to 

 relax from their devotion, and to despair of retain- 

 ing the homage which so many ages have paid to 

 the idol of reflective thought. 



Mr. Ribot's recent work on contemporary Ger- 

 man psychology seeks to maintain and widen this 

 breach between the two sciences : and we cannot 

 but regret that it should be so ; for they are really 

 distinct sciences, running parallel with each other, 

 and have no more reason to come into conflict with 

 each other than physics and chemistry. Their 

 methods may be different, but are not on that 



account contradictory ; and the one should not be 

 made all-absorbing to the prejudice of the other. 



We frankly admit, however, that it is no wonder 

 the scientist, accustomed as he is to experiment 

 and definite results, feels a sense of dissatisfac- 

 tion with the study against which psychophys- 

 ics presents the charge of obscurity. Kantian 

 and post-Kantian psychology has never been 

 characterized by perspicuity ; and it is a natural 

 revolt against it that even speculative Germany 

 seems to have abandoned the poi^ular gods of 

 philosophy to find a new worship in experiments 

 and facts quite in contrast with the genius of that 

 people, disposed in so many particulars to take the 

 high a priori road to truth, and to project every 

 thing from consciousness, as it is accused of doing. 

 Hence there is something of justice in the claim of 

 psychophysics : it does tend to make its conclusions 

 intelligible to experience ; and that is a very great 

 gain. But, with these legitimate claims to our 

 respect, it should not usurp the whole province of 

 psychological experience, which it does not do, 

 nor repudiate introspection as a proper source and 

 method of knowledge, which it is too much dis- 

 posed to do, forgetful of the fact that in so doing 

 it really undermines the final test of its own results. 



The field of psychophysics is much more limited 

 than one would at first suspect. Its name might 

 imply at least a partial combination of physiology 

 and psychology : but its advocates exclude the 

 main and distinctive features of both these sciences 

 from it, and assign it a very limited territory ; as 

 Dr. Wundt afiirms, the field ' between inner and 

 outer experience.' This means that it confines its 

 investigations to phenomena which intermediate 

 between purely mechanical events and purely 

 reflective consciousness. Hence, on the one hand, 

 such phenomena as circulation, assimilation, diges- 

 tion, and on the other, such as perception, judg- 

 ment, reasoning, memor}^ and imagination, are 

 excluded from the field of its inquiries. Thus it 

 is limited to the phenomena of sensation, which 

 constitute the intermediate class spoken of. But 

 even this class is not considered in its qualitative, 

 but only its quantitative relations, hence it is still 

 more limited. These quantitative characteristics 

 consist of their intensity, psychic constancy, and 

 reaction time. The last may be included under 

 that of psychic constants, making two distinct 

 problems for psychophysical investigation. That 

 of the psychic constants is the more important of 

 the two, as it has a bearing upon the speculative 



